Tongyang Huoxue Decoction(TYHX)synergistically regulates calcium homeostasis and mitochondrial unfolded protein response in ischemia-reperfusion injured sinus node cells via SERCA2aOA

Background:Tongyang Huoxue Decoction(TYHX)can modulate calcium homeostasis andmitochondrial quality management to safeguard sinus node function.Nonetheless,theprecise chemical process remains unclear.This study aimed to verify the upstreamregulatory influence of SERCA2a on the enhancement of calcium homeostasis andmitochondrial unfolded protein response(mtUPR)in sinus node cells(SANCs)by TYHX,while elucidating the protective mechanism of TYHX on SNC activity.Methods:In vitromodels of sh/ad-SERCA2a and si-β-tubulin were established,and TYHX was employed tointervene in each cell group.Various approaches were employed to detect functionsincluding mitochondrial membrane potential,mitochondrial respiration,oxidative stress,mitochondrial biosynthesis,and mitochondrial autophagy and UPR.In vivo confirmationthat TYHX suppresses apoptosis and inflammatory injury.Results:I/R injury led todiminished SANCs activity,compromised mitochondrial membrane potential,reducedmitochondrial respiratory function,and heightened oxidative stress.This further impededmitochondrial production,destabilized the proteome structure,triggered the mtUPR,andinhibited mitochondrial autophagy,thereby upsetting the dynamic equilibrium of themitochondrial quality control network.Furthermore,I/R injury intensified intracellularcalcium excess and worsened oxidative stress damage.Conversely,TYHX interventionmitigated intracellular calcium overload,augmented mitochondrial antioxidant capacity,stimulated mitochondrial autophagy,and decreased the mtUPR.Sh-SERCA2a counteractedthe regulatory influences of TYHX on calcium homeostasis,mitochondrial biogenesis,mtUPR,mitochondrial autophagy,and apoptosis.Conversely,ad-SERCA2a exerted minimalinfluence on the efficacy of TYHX.SERCA2a is a major target protein for TYHX todemonstrate its efficacy.When tubulin expression was minimal,there was no statisticallysignificant difference in the expression levels of mitochondrial autophagy,mitochondrialbiosynthesis,calcium homeostasis regulation,and mtUPR between the sh-SERCA2a andad-SERCA2a groups.This indicates that the normal expression of tubulin is essential forSERCA2a to enhance the efficiency of TYHX.Tubulin may serve as an upstream regulatorymolecule of SERCA2a.In vivo tests confirmed that TYHX may suppress apoptosis andmitigate cellular inflammatory damage.Conclusion:TYHX preserved intracellular calciumequilibrium,mitigated mitochondrial oxidative stress,sustained mitochondrial stability,enhanced mitochondrial biosynthesis,suppressed the mtUPR,facilitated mitochondrialautophagy,and inhibited apoptosis viaβ-tubulin-SERCA2a,thereby safeguarding sinus nodefunctionality from I/R injury.